In the POR sequence, right after the D+/D- detection, the charger initiates an ADC reading on the VBUS pin voltage without any load current (VBUS at no load condition, VBUS₀) before the converter starts switching. The default VINDPM threshold is set to be VBUS₀ - 1.4 V (VBUS₀ >= 7 V) or VBUS₀ - 0.7V (VBUS₀ < 7 V).

The VBUS₀ can be remeasured at any time by setting the register bit FORCE_VINDPM_DET=1. The converter stops switching, the ADC measures the VBUS voltage, the VINDPM register field is updated, and then the FORCE_VINDPM_DET bit returns to 0. The force VINDPM detection only can be done when VSYS_STAT = 0 (VBAT > VSYSMIN), otherwise stopping the converter would cause VSYS to drop below VSYSMIN. If VSYS_STAT = 1 (VBAT < VSYSMIN), VBUS₀ measurement does not start, the FORCE_VINDPM_DET bit resets to 0 and the VINDPM register retains its current value. The host must ensure there is a battery present prior to setting FORCE_VINDPDM_DET = 1, or to allow system to be supported by the battery during detection.

When the measured VBUS₀ is out of the VINDPM register range, the changer sets the VINDPM register to the minimum value (3.6V) or maximum (22V) value as appropriate.